As with many "tech innovations" in the transportation space, this rapidly turns into reinventing the bus. #3 in particular is just "the bus, but more frequent" which you can do by simply increasing bus frequency dramatically, which most American cities should already be doing but don't, because of their budget priorities and the stigma of buses as something for poor people.

I definitely agree that cities should invest more in their transit infrastructure. But at any given budget level AVs have the potential to dramatically increase service quality. Drivers are the biggest costs in providing bus services and they scale with frequency and coverage.